The present invention relates to a mine ventilation structure used to block a passageway or to prevent mixture of ventilation air at the intersection of two passageways. The ventilation structure blocking a passageway can be a shaft partition, stopping or regulator. The ventilation structure preventing the mixture of ventilation air at the intersection of two passageways can be an overcast or an undercast.
In an underground mine having a grid of intersecting passageways separated by columns of remaining material, there is need for a ventilation system as the mining activity becomes more distant from a source of ventilation. In a typical ventilation system, intake air and return air are ducted through air shafts formed by selected passageways. Along the air shafts, intersecting passageways are blocked with a partition or ducted through an overcast or an undercast.
The return air in a coal mine contains coal dust and methane so it is important that there is no intermingling of the return air with the intake air. Permanent barriers, such as those constructed of concrete block, steel plates or the like, have been used to define the passageways forming the air shafts. Even though the prior art structures are treated with sealants, a significant amount of air leaks through these structures, heard in the mine as a sucking sound. At an overcast or undercast, the leaks result in intermingling of the return and intake air at the barriers resulting in a significant loss of pressure when repeated at multiple barriers along shafts that may extend for thousands of feet.
In addition to leaking air, prior art partitions, overcasts and undercasts made of concrete blocks, steel plates and the like, require large amounts of materials that are heavy and difficult to transport and handle in the confined space within a mine, and the structures are very time consuming to construct.
As mining advance rates become faster, installation rates of ventilation overcasts and ventilation stoppings have to increase. Ventilation overcast and stopping sites are either cut out of the roof of the mine with a continuous miner or shot out with explosives. Either method of removing the roof leaves the surrounding rock walls uneven and jagged. The rough wall faces makes sealing of mine stoppings or the wing walls of the overcast extremely difficult.